In many communication systems, an oscillator is employed to generate a reference oscillating signal from which other signals or clocks are produced. For example, the reference oscillating signal may be used to generate one or more clocks for driving digital and analog circuitry. Additionally, the reference oscillating signal may be employed in a local oscillator (LO) for downconverting radio frequency (RF), intermediate frequency (IF), or other signals to lower or baseband frequencies, and/or for upconverting baseband signals to IF, RF, or other higher frequencies.
Many of these communication systems are portable systems, such as cellular telephones, personal digital assistants (PDAs), handheld devices, and other portable communication devices. These portable communication systems typically rely on a limited power source, such as a battery, to perform the various intended operations. A limited power source typically has a continuous use lifetime that depends on the amount of power used by the portable device. It is generally desired to extend the continuous use lifetime as much as possible. Accordingly, portable communication systems are more frequently designed to consume less and less power.
With regard to oscillators, they are typically designed to consume substantially more power necessary to ensure the continuous generation of an oscillation signal. For portable devices, such excess power consumption may significantly impact the continuous use lifetime of the devices. Thus, there is a need for a more power efficient method and apparatus for generating an oscillating signal.